Anxiety disorders are the most common mental health problem in youth and are associated with significant disability and risk of recurrent and new onset psychopathology. Although strong evidence exists for the efficacy of CBT and antidepressants for anxiety, there are significant barriers impeding uptake of these interventions in clinical practice, contributing to lowest rate of treatment for this disorder for any youth diagnostic category (fewer than 1 in 3 youth). In order to address the public health need for low-cost, effective, accessible, and easy-to-disseminate services for youth anxiety, this application tests computerized Cognitive Bias Modification (CBM) as a novel, alternative treatment with few or none of the barriers to uptake associated with extant evidence-based treatments. We will conduct a large (N = 498 ), randomized efficacy-effectiveness trial of CBM in youth ages 12 to 17, examined against the background of underlying treatment as usual (TAU). In this RCT, we test the level of support (scaffolding) needed to adequately deliver a self-administered variant of CBM to anxious youth, in preparation for future deployment- focused trials. Youth are randomized to either: a minimally effective attention-control version of the CBM program (Arm 1); self-administered active CBM that is downloaded and installed on participants' home computers (Self-Administered CBM-only; Arm 2), or to self-administered active CBM paired with an adherence promotion (AP) component delivered via brief telephone calls from study coaches, including brief motivational enhancement and/or technical assistance (Self-Administered CBM+AP; Arm 3). CBM sessions occur 3 times weekly over 4 weeks (12 total). Follow-up assessments occur at 1, 3, 6 and 12 months post- enrollment. Compared to the control condition, we hypothesize that both active CBM conditions will yield greater anxiety diagnosis remission, and greater improvement for secondary outcomes anxiety and depressive symptoms and functioning. We also hypothesize that CBM+AP (Arm 3) will yield greater anxiety diagnosis remission and greater improvement in secondary outcomes, compared to CBM-only (Arm 2). We also will conduct cost effectiveness analyses and hypothesize that the incremental cost per unit of anxiety- free days and health-related quality of life will be lower for active CBM (Arm 2 + Arm 3) relative to the control condition (Arm 1). We will explore moderation and fidelity factors to inform future dissemination efforts; e.g,, whether CBM is robust to variation in youth clinical and demographic characteristics. We will test whether the CBM+AP condition results in higher participant engagement and compliance compared to the conditions without AP (Arm 3 vs. Arms 1 + 2). Finally, we will examine the mediating role of attention-bias change in producing CBM effects. Should CBM prove efficacious for anxiety and easily deliverable in this at-home, self- administered format, it will permit the broader deployment of a novel anxiety EBT to youth in great need.